I don't know, I think it's Allen but it'll be too much of a burden for him with all those things as well such as being the destroyer of time and what not and the 14th player etc. It could be someone totally new though, you realize like Kanda or Lavi or some new character since the anime is still on going and they are introducing new characters all the time

I know that in the manga, they're trying to lead you to believe it's Lenalee. But, it could still be Allen, because his innocence somehow, magically, couldn't be destroyed. And, I'm still holding out for the last big twist to be finding out Allen's innocence is the Sacred Heart. :3